Improve reseting functionality

[tomalec]

As a part of Palindrom/Palindrom#90 reset method was implemented, it takes initial object and entire new JSON, to convert it into JSON Patch to be applied.

I think as we are using JSON Patch communication over WebSocket, reset (if possible) should also be communicated with JSON Patch:

[
    {op: "replace", path: "/server/sender/version", value: 7},
    {op: "replace", path: "", value: entireJSONTree}
]

As that is exactly what we need.

"Set sender's version to given - regardless of queue or any existing version"
"Replace your outdated tree, with new one, entirely"

@chrhol, @warpech WDYT?

@chrhol I will need your support in making Starcounter respond such way for /reconnect request